I recall Chevy S-10 models having similar intermittent dash cluster problems.
Left lower dash pad attachment point was also a common ground buss.
Many black wires terminated with round eyelets.
All of them with a few star washers under that dash pad bolt.
When the dash attachment bolt loosened, loss of ground.
Lack of ground can be just as troublesome as lack of power.

Don't know if you have one, but one of the first things I bought when I got my 2004 corvette was a OBD code reader ( this one). It can read GM specific trouble codes from all of the car's computers / modules.

It has been worth it's weight in gold to me. Some of the issues you are having could point to the ignition switch, bad key (check the resistor chip on your key - make sure it is clean), or your body control module on it's way out.

A good code scanner should be able to diagnose a communication error between your ignition switch and the BCM if that is the issue, or with VATS / Passkey.

One thing - have your battery checked. If the BCM doesn't get the voltage it wants, it will go absolutely nuts.

If you still want to get rid of Passkey or VATS, you will need a Tech2 or a tuning module to get rid of it the right way.

GM at that time had three different security systems. VATS was used in passenger cars, the first system, had a black and silver wafer chip on the key shank between the key head and the key cuts, that is the one that was easily bypassed with a resistor. Replacements are determined by a key reader, a VATS decoder that can be used to determine the VATS code from a key or by decoding the lock module in the car, a number from 1 to 15 in the parts book together with cutting the replacement key to turn the lock cylinder.

Next one uses a transponder in the key head, Passkey, both can be identified by stampings on the key shank, either the letters and number "PK3" or a circle with a plus mark in the center, those are a different system, the key is programmed to the car after the key is cut to turn the lock cylinder by two procedures, one if a key is available and another as a reprogram if all keys are lost. Basically those two systems, the vehicle is programmed to "accept" the new key's signal that is transmitted to the BCM or security module dependent on the vehicle. PK# keys were used in passenger cars, in the early 2000 decade they used the "circle plus" key though I can't remember seeing trucks so equipped (available option on trucks), only passenger cars.

The last system used a sensor and magnet in the lock cylinder, that is the system most likely this truck has. Basically the two have to align up to send the signal to allow it to start. Trucks and some lower end cars like the Cavalier had that system. Replacement keys look similar to the ones I mentioned in the second paragraph but with no markings on the key shank in the area between the head and the tooth portion of the shank. All it takes for those keys is to cut the teeth in the shank, put it in the lock cylinder and turn to start. If the lock cylinder is fully functional the car should start. Worn lock cylinder, bad sensor or wiring could be the problem.

Now, one last one that nobody has touched on. The G Series vans (Savanna and Express) suffer from one of the STUPIDEST things known to mankind, putting the ECM/PCM/VCM (computer, different names for different brands/models) under the hood in the engine compartment where water, dirt, salt and corrosion can wreak havoc with them. If that aluminum case gets compromised due to corrosion, I've seen them swelled up and full of moisture. I had one fleet that would routinely take their delivery vans and relocate the computer to inside the passenger compartment, it only took them about two or three core charges for an unacceptable one to turn in for a refund to do this. Might also be something to look into.

RB211 suggested that I get a code scanner. The service shop that I use has a very sophisticated scanner, way over a layman's budget. There were no codes stored. The suggestion of possible weak battery has been ruled out. The starter turns over vigorously.

The key is not a smart key. It is just a plain old cheap key, no chip.

Having read egregore's posts, it seems likely that the PassLock is a red herring; the totally blacked out instrument cluster, when the intermittent problem rears its ugly head, does make it look like a power or ground problem.

The truck is at the maintenance shop; I'll drop by in the morning and discuss troubleshooting for power or ground problems.

Frustrating, I'm way behind on re-supply trips to the stores that are my customers, but I am not going to drive the truck if I am not confidant that it will start when I'm ready to leave a customer location.

Logic says that if the BCM is failing it should throw a code. But logic has been thwarted by automotive electronics before. Have they tried that yet?

quote:

Originally posted by Greymann:
This may help, I haven't used it.
It's a module to replace the factory body module. Eliminates passlock.

https://newrockies.com/

https://newrockiesinc.zendesk....ess?mobile_site=true

I used this on an 02 Tahoe. It did require the computer to be “reflashed”

quote:

Originally posted by shovelhead:

Now, one last one that nobody has touched on. The G Series vans (Savanna and Express) suffer from one of the STUPIDEST things known to mankind, putting the ECM/PCM/VCM (computer, different names for different brands/models) under the hood in the engine compartment where water, dirt, salt and corrosion can wreak havoc with them.

My first post touched on this.

It has been almost a month. Any luck?

I got rid of an Impala over this very thing. It had to sit for 10 min with the ignition off to reset. It left me stranded several times at very inconvenient times.

Had the same problem with a 2004 Colorado. Local mechanic went through the entire truck with no luck finding anything.. Told me to get a new key made. (No chip) Solved the problem. Drove it another 5 yrs without trouble.


o5

quote:

Originally posted by egregore:

quote:

Originally posted by shovelhead:

Now, one last one that nobody has touched on. The G Series vans (Savanna and Express) suffer from one of the STUPIDEST things known to mankind, putting the ECM/PCM/VCM (computer, different names for different brands/models) under the hood in the engine compartment where water, dirt, salt and corrosion can wreak havoc with them.

My first post touched on this.

OOPS! I apologize! Old age is catching up on me.

quote:

Originally posted by egregore:

It has been almost a month. Any luck?

Nope. The shop that I use is "trouble-shooting" by turning the key on several times a day, waiting for the instrument panel to stay blacked out.

They did remove the fuse box to verify that all connections are solid and corrosion-free.

Until the problem is identified, my strategy is to leave the engine running while I am at any customer location. Never shut it down unless I am in a "safe" location, like my own driveway, or the hangar at the airport. Return it to the maintenance shop when not in use, so that they can continue to try it every hour or so.

Not an ideal solution, not by far.

We have laughingly thought about a road trip to the egregore facility in Tennessee. Or, do you make "house calls?" The Orlando area is very nice, this time of the year.